1
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DiMucci IM, Titus CJ, Nordlund D, Bour JR, Chong E, Grigas DP, Hu CH, Kosobokov MD, Martin CD, Mirica LM, Nebra N, Vicic DA, Yorks LL, Yruegas S, MacMillan SN, Shearer J, Lancaster KM. Scrutinizing formally Ni IV centers through the lenses of core spectroscopy, molecular orbital theory, and valence bond theory. Chem Sci 2023; 14:6915-6929. [PMID: 37389249 PMCID: PMC10306094 DOI: 10.1039/d3sc02001k] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 05/30/2023] [Indexed: 07/01/2023] Open
Abstract
Nickel K- and L2,3-edge X-ray absorption spectra (XAS) are discussed for 16 complexes and complex ions with nickel centers spanning a range of formal oxidation states from II to IV. K-edge XAS alone is shown to be an ambiguous metric of physical oxidation state for these Ni complexes. Meanwhile, L2,3-edge XAS reveals that the physical d-counts of the formally NiIV compounds measured lie well above the d6 count implied by the oxidation state formalism. The generality of this phenomenon is explored computationally by scrutinizing 8 additional complexes. The extreme case of NiF62- is considered using high-level molecular orbital approaches as well as advanced valence bond methods. The emergent electronic structure picture reveals that even highly electronegative F-donors are incapable of supporting a physical d6 NiIV center. The reactivity of NiIV complexes is then discussed, highlighting the dominant role of the ligands in this chemistry over that of the metal centers.
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Affiliation(s)
- Ida M DiMucci
- Department of Chemistry and Chemical Biology, Cornell University, Baker Laboratory 162 Sciences Drive Ithaca NY 14853 USA
| | - Charles J Titus
- Department of Physics, Stanford University Stanford California 94305 USA
| | - Dennis Nordlund
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory Menlo Park California 94025 USA
| | - James R Bour
- Department of Chemistry, University of Michigan Ann Arbor Michigan 48109 USA
| | - Eugene Chong
- Department of Chemistry, University of Michigan Ann Arbor Michigan 48109 USA
| | - Dylan P Grigas
- Department of Chemistry and Chemical Biology, Cornell University, Baker Laboratory 162 Sciences Drive Ithaca NY 14853 USA
| | - Chi-Herng Hu
- Department of Chemistry, University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA
| | | | - Caleb D Martin
- Department of Chemistry and Biochemistry, Baylor University Waco Texas 76798 USA
| | - Liviu M Mirica
- Department of Chemistry, University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA
| | - Noel Nebra
- Laboratoire Hétérochimie Fondamentale et Appliquée (LHFA), Université Paul Sabatier, CNRS 118 Route de Narbonne 31062 Toulouse France
| | - David A Vicic
- Department of Chemistry, Lehigh University Bethlehem Pennsylvania 18015 USA
| | - Lydia L Yorks
- Department of Chemistry, Lehigh University Bethlehem Pennsylvania 18015 USA
| | - Sam Yruegas
- Department of Chemistry and Biochemistry, Baylor University Waco Texas 76798 USA
| | - Samantha N MacMillan
- Department of Chemistry and Chemical Biology, Cornell University, Baker Laboratory 162 Sciences Drive Ithaca NY 14853 USA
| | - Jason Shearer
- Department of Chemistry, Trinity University San Antonio Texas 78212-7200 USA
| | - Kyle M Lancaster
- Department of Chemistry and Chemical Biology, Cornell University, Baker Laboratory 162 Sciences Drive Ithaca NY 14853 USA
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2
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Hu CH, Kim ST, Baik MH, Mirica LM. Nickel-Carbon Bond Oxygenation with Green Oxidants via High-Valent Nickel Species. J Am Chem Soc 2023; 145:11161-11172. [PMID: 37183827 DOI: 10.1021/jacs.3c01012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Described herein is the synthesis of the NiII complex (tBuMe2tacn)NiII(cycloneophyl) (tBuMe2tacn = 1-tert-butyl-4,7-dimethyl-1,4,7-triazacyclononane, cycloneophyl = -CH2CMe2-o-C6H4-) and its reactivity with dioxygen and peroxides. The new tBuMe2tacn ligand is designed to enhance the oxidatively induced bond-forming reactivity of high-valent Ni intermediates. Tunable chemoselectivity for Csp2-O vs Csp2-Csp3 bond formation was achieved by selecting the appropriate solvent and reaction conditions. Importantly, the use of cumene hydroperoxide and meta-chloroperbenzoic acid suggests a heterolytic O-O bond cleavage upon reaction with (tBuMe2tacn)NiII(cycloneophyl). Mechanistic studies using isotopically labeled H2O2 support the generation of a high-valent Ni-oxygen species via an inner-sphere mechanism and subsequent reductive elimination to form the Csp2-O bond. Kinetic studies of the exceptionally fast Csp2-O bond-forming reaction reveal a first-order dependence on both (tBuMe2tacn)NiII(cycloneophyl) and H2O2, and thus an overall second-order reaction. Eyring analysis further suggests that the oxidation of the NiII complex by H2O2 is the rate-determining step, which can be modulated by the presence of coordinating solvents. Moreover, computational studies fully support the conclusions drawn from experimental results. Overall, this study reveals for the first time the ability to control the oxidatively induced C-C vs C-O bond formation reactions at a Ni center. Importantly, the described system merges the known organometallic reactivity of Ni with the biomimetic oxidative transformations resembling oxygenases and peroxidases, and involving high-valent metal-oxygen intermediates, which is a novel approach that should lead to unprecedented oxidative catalytic transformations.
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Affiliation(s)
- Chi-Herng Hu
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, Illinois 61801, United States
| | - Seoung-Tae Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Mu-Hyun Baik
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Liviu M Mirica
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, Illinois 61801, United States
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3
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Green KA, Honeycutt AP, Ciccone SR, Grice KA, Baur A, Petersen JL, Hoover JM. A Redox Transmetalation Step in Nickel-Catalyzed C-C Coupling Reactions. ACS Catal 2023; 13:6375-6381. [PMID: 37180967 PMCID: PMC10167653 DOI: 10.1021/acscatal.2c06015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 04/11/2023] [Indexed: 05/16/2023]
Abstract
Ni-catalyzed C-H functionalization reactions are becoming efficient routes to access a variety of functionalized arenes, yet the mechanisms of these catalytic C-C coupling reactions are not well understood. Here, we report the catalytic and stoichiometric arylation reactions of a nickel(II) metallacycle. Treatment of this species with silver(I)-aryl complexes results in facile arylation, consistent with a redox transmetalation step. Additionally, treatment with electrophilic coupling partners generates C-C and C-S bonds. We anticipate that this redox transmetalation step may be relevant to other coupling reactions that employ silver salts as additives.
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Affiliation(s)
- Kerry-Ann Green
- C.
Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Aaron P. Honeycutt
- C.
Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Sierra R. Ciccone
- C.
Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Kyle A. Grice
- Department
of Chemistry and Biochemistry, DePaul University, Chicago, Illinois 60614, United States
| | - Andreas Baur
- C.
Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Jeffrey L. Petersen
- C.
Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Jessica M. Hoover
- C.
Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
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4
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The once-elusive Ni(IV) species is now a potent candidate for challenging organic transformations. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2022.214849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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5
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Schallenberg D, Pardemann N, Villinger A, Seidel WW. Synthesis and coordination behaviour of 1 H-1,2,3-triazole-4,5-dithiolates. Dalton Trans 2022; 51:13681-13691. [PMID: 36000523 DOI: 10.1039/d2dt00410k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The preparative access to and first group 10 metal complexes of novel 1H-1,2,3-triazole-4,5-dithiolate ligands (tazdt2-) are reported. A set of S-protected 1H-1,2,3-triazole-4,5-dithiol derivatives with R1 = 2,6-dimethylphenyl (Xy) or benzyl (Bn) at N1 and with R2 = Bn or trimethylsilylethyl (TMS-ethyl) at both S atoms were synthesized by a 1,3-dipolar cycloaddition catalysed by either Ru(II) or Cu(I). Extensive investigations on the removal of the protective groups resulted the reductive removal of benzyl groups to be superior in isolating the free 4,5-dithiols of R1N3C2(SH)2 with R1 = Xy (H2-8) or Bn (H2-9). Coordination of these ligands led to the formation of the metal complexes [(η5-C5H5)2Ti(8)], [Ni(dppe)(8)], [Ni(dppe)(9)], [Pd(dppe)(9)] {dppe = bis(diphenylphosphanyl)ethane} and homoleptic (NBu4)n[Ni(8)2] (n = 1, 2). All complexes were fully characterized including structure determination by single crystal XRD. The electronic properties of the Ni and Pd complexes were determined by cyclic voltammetry, UV/vis and EPR spectroscopy supported by DFT calculations. According to the spectral and electrochemical data, the tazdt2- complexes resemble the corresponding benzene-1,2-dithiolate (bdt2-) type compounds reflecting the restricted influence of the electron-withdrawing N3 moiety in the backbone. DSC-TGA measurements with [(η5-C5H5)2Ti(8)] and [Ni(dppe)(8)] indicate a well-defined thermal process involving simultaneous elimination of both N2 and CS.
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Affiliation(s)
- David Schallenberg
- Institut für Chemie, Universität Rostock, Albert-Einstein-Straße 3a, 18059 Rostock, Germany.
| | - Nils Pardemann
- Institut für Chemie, Universität Rostock, Albert-Einstein-Straße 3a, 18059 Rostock, Germany.
| | - Alexander Villinger
- Institut für Chemie, Universität Rostock, Albert-Einstein-Straße 3a, 18059 Rostock, Germany.
| | - Wolfram W Seidel
- Institut für Chemie, Universität Rostock, Albert-Einstein-Straße 3a, 18059 Rostock, Germany. .,Leibniz Institut für Katalyse e.V., Albert-Einstein-Straße 29a, 18059 Rostock, Germany
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6
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Deciphering the mechanism of the Ni-photocatalyzed C‒O cross-coupling reaction using a tridentate pyridinophane ligand. Nat Commun 2022; 13:1313. [PMID: 35288558 PMCID: PMC8921334 DOI: 10.1038/s41467-022-28948-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 02/10/2022] [Indexed: 01/23/2023] Open
Abstract
Photoredox nickel catalysis has emerged as a powerful strategy for cross-coupling reactions. Although the involvement of paramagnetic Ni(I)/Ni(III) species as active intermediates in the catalytic cycle has been proposed, a thorough spectroscopic investigation of these species is lacking. Herein, we report the tridentate pyridinophane ligands RN3 that allow for detailed mechanistic studies of the photocatalytic C–O coupling reaction. The derived (RN3)Ni complexes are active catalysts under mild conditions and without an additional photocatalyst. We also provide direct evidence for the key steps involving paramagnetic Ni species in the proposed catalytic cycle: the oxidative addition of an aryl halide to a Ni(I) species, the ligand exchange/transmetalation at a Ni(III) center, and the C–O reductive elimination from a Ni(III) species. Overall, the present work suggests the RN3 ligands are a practical platform for mechanistic studies of Ni-catalyzed reactions and for the development of new catalytic applications. Mechanistic knowledge of photocatalytic nickel reactions is lacking, particularly with regards to the identities and oxidation states of key intermediates. Here the authors report a class of tridentate ligands that enables in-depth study of a representative cross-coupling reaction, wherein evidence for multiple intermediates in a Ni(I/III) cycle is presented.
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7
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Affiliation(s)
- Victor M. Chernyshev
- Platov South-Russian State Polytechnic University (NPI), Novocherkassk, 346428, Russia
| | - Valentine P. Ananikov
- Platov South-Russian State Polytechnic University (NPI), Novocherkassk, 346428, Russia
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, 119991, Russia
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8
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He H, Ye Z, Shimizu D, Sumra I, Zhang Y, Liang Z, Zeng Y, Xu L, Osuka A, Ke Z, Jiang HW. Formation of Stable Ni III N-Confused Porphyrins Aided by a 3-Ethoxy Group. Chemistry 2021; 28:e202103272. [PMID: 34672400 DOI: 10.1002/chem.202103272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Indexed: 11/08/2022]
Abstract
We report the synthesis, characterization, and reactivities of two stable NiIII N-confused porphyrin (NCP) complexes. Metalation of 3-OEt NCP 1 with NiCl2 ⋅ 6H2 O in CHCl3 /EtOH gave 3-OEt NiII NCP 3 initially, which was easily oxidized in air to form the NiIII complex of NCP inner C-oxide 4. Bis-ethoxy-modified NiIII complex 5 was synthesized by oxidation of 3 with PIFA in ethanol and CHCl3 . The structures of 4 and 5 were determined by single-crystal X-ray diffraction analysis. An unusually long NiIII -C bond (2.170(9) Å) was observed in 4. The g-factor (g>2.1) observed in the EPR spectra of 4 and 5 further confirmed that they are paramagnetic NiIII complexes. Comparative experiments showed that the 3-ethoxy group plays an important role in the formation of 4 and 5. Reduction of 4 and 5 with NaBH4 regenerated complex 3.
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Affiliation(s)
- Huowang He
- School of Chemistry, South China Normal University and Key Laboratory of Environment, Ministry of Education, School of Chemistry, South China Normal University, Guangzhou, 510006, P. R. China
| | - Zongren Ye
- School of Materials Science & Engineering, PCFM Lab, Sun Yat-sen University, Guangzhou, 510275, P. R. China
| | - Daiki Shimizu
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan
| | - Idrees Sumra
- School of Chemistry, South China Normal University and Key Laboratory of Environment, Ministry of Education, School of Chemistry, South China Normal University, Guangzhou, 510006, P. R. China
| | - Yihuan Zhang
- School of Chemistry, South China Normal University and Key Laboratory of Environment, Ministry of Education, School of Chemistry, South China Normal University, Guangzhou, 510006, P. R. China
| | - Zhengyu Liang
- School of Chemistry, South China Normal University and Key Laboratory of Environment, Ministry of Education, School of Chemistry, South China Normal University, Guangzhou, 510006, P. R. China
| | - Yingyu Zeng
- School of Chemistry, South China Normal University and Key Laboratory of Environment, Ministry of Education, School of Chemistry, South China Normal University, Guangzhou, 510006, P. R. China
| | - Ling Xu
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Key Laboratory of Application and Assemble of Organic Functional molecules, Hunan Normal University, Changsha, 410081, P. R. China
| | - Atsuhiro Osuka
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Zhuofeng Ke
- School of Materials Science & Engineering, PCFM Lab, Sun Yat-sen University, Guangzhou, 510275, P. R. China
| | - Hua-Wei Jiang
- School of Chemistry, South China Normal University and Key Laboratory of Environment, Ministry of Education, School of Chemistry, South China Normal University, Guangzhou, 510006, P. R. China
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9
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Walker BR, Manabe S, Brusoe AT, Sevov CS. Mediator-Enabled Electrocatalysis with Ligandless Copper for Anaerobic Chan-Lam Coupling Reactions. J Am Chem Soc 2021; 143:6257-6265. [PMID: 33861580 PMCID: PMC8143265 DOI: 10.1021/jacs.1c02103] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Simple copper salts serve as catalysts to effect C-X bond-forming reactions in some of the most utilized transformations in synthesis, including the oxidative coupling of aryl boronic acids and amines. However, these Chan-Lam coupling reactions have historically relied on chemical oxidants that limit their applicability beyond small-scale synthesis. Despite the success of replacing strong chemical oxidants with electrochemistry for a variety of metal-catalyzed processes, electrooxidative reactions with ligandless copper catalysts are plagued by slow electron-transfer kinetics, irreversible copper plating, and competitive substrate oxidation. Herein, we report the implementation of substoichiometric quantities of redox mediators to address limitations to Cu-catalyzed electrosynthesis. Mechanistic studies reveal that mediators serve multiple roles by (i) rapidly oxidizing low-valent Cu intermediates, (ii) stripping Cu metal from the cathode to regenerate the catalyst and reveal the active Pt surface for proton reduction, and (iii) providing anodic overcharge protection to prevent substrate oxidation. This strategy is applied to Chan-Lam coupling of aryl-, heteroaryl-, and alkylamines with arylboronic acids in the absence of chemical oxidants. Couplings under these electrochemical conditions occur with higher yields and shorter reaction times than conventional reactions in air and provide complementary substrate reactivity.
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Affiliation(s)
- Benjamin R Walker
- Department of Chemistry and Biochemistry, The Ohio State University, 151 W. Woodruff Avenue, Columbus, Ohio 43210, United States
| | - Shuhei Manabe
- Department of Chemistry and Biochemistry, The Ohio State University, 151 W. Woodruff Avenue, Columbus, Ohio 43210, United States
| | - Andrew T Brusoe
- Chemical Development, Boehringer Ingelheim Pharmaceuticals, Inc., 900 Ridgebury Road, P.O. Box 368, Ridgefield, Connecticut 06877-0368, United States
| | - Christo S Sevov
- Department of Chemistry and Biochemistry, The Ohio State University, 151 W. Woodruff Avenue, Columbus, Ohio 43210, United States
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10
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Kisgeropoulos EC, Manesis AC, Shafaat HS. Ligand Field Inversion as a Mechanism to Gate Bioorganometallic Reactivity: Investigating a Biochemical Model of Acetyl CoA Synthase Using Spectroscopy and Computation. J Am Chem Soc 2021; 143:849-867. [PMID: 33415980 DOI: 10.1021/jacs.0c10135] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The biological global carbon cycle is largely regulated through microbial nickel enzymes, including carbon monoxide dehydrogenase (CODH), acetyl coenzyme A synthase (ACS), and methyl coenzyme M reductase (MCR). These systems are suggested to utilize organometallic intermediates during catalysis, though characterization of these species has remained challenging. We have established a mutant of nickel-substituted azurin as a scaffold upon which to develop protein-based models of enzymatic intermediates, including the organometallic states of ACS. In this work, we report the comprehensive investigation of the S = 1/2 Ni-CO and Ni-CH3 states using pulsed EPR spectroscopy and computational techniques. While the Ni-CO state shows conventional metal-ligand interactions and a classical ligand field, the Ni-CH3 hyperfine interactions between the methyl protons and the nickel indicate a closer distance than would be expected for an anionic methyl ligand. Structural analysis instead suggests a near-planar methyl ligand that can be best described as cationic. Consistent with this conclusion, the frontier molecular orbitals of the Ni-CH3 species indicate a ligand-centered LUMO, with a d9 population on the metal center, rather than the d7 population expected for a typical metal-alkyl species generated by oxidative addition. Collectively, these data support the presence of an inverted ligand field configuration for the Ni-CH3 Az species, in which the lowest unoccupied orbital is centered on the ligands rather than the more electropositive metal. These analyses provide the first evidence for an inverted ligand field within a biological system. The functional relevance of the electronic structures of both the Ni-CO and Ni-CH3 species are discussed in the context of native ACS, and an inverted ligand field is proposed as a mechanism by which to gate reactivity both within ACS and in other thiolate-containing metalloenzymes.
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Affiliation(s)
- Effie C Kisgeropoulos
- Department of Chemistry and Biochemistry and Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, United States
| | - Anastasia C Manesis
- Department of Chemistry and Biochemistry and Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, United States
| | - Hannah S Shafaat
- Department of Chemistry and Biochemistry and Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, United States
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11
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Xue Z, Yu H, He J, Zhang Y, Lan X, Liu R, Zhang L, Mu T. Highly Efficient Cleavage of Ether Bonds in Lignin Models by Transfer Hydrogenolysis over Dual-Functional Ruthenium/Montmorillonite. CHEMSUSCHEM 2020; 13:4579-4586. [PMID: 32419386 DOI: 10.1002/cssc.202000978] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 05/17/2020] [Indexed: 06/11/2023]
Abstract
Cleavage of ether bonds is a crucial but challenging step for lignin valorization. To efficiently realize this transformation, the development of robust catalysts or catalytic systems is required. In this study, montmorillonite (MMT)-supported Ru (denoted as Ru/MMT) is fabricated as a dual-functional heterogeneous catalyst to cleave various types of ether bonds through transfer hydrogenolysis without using any additional acids or bases. The prepared Ru/MMT material is found to efficiently catalyze the cleavage of various lignin models and lignin-derived phenols; cyclohexanes (fuels) and cyclohexanols (key intermediates) are the main products. The synergistic effect between electron-enriched Ru and the acidic sites on MMT contributes to the excellent performance of Ru/MMT. Systematic studies reveal that the reaction proceeds through two possible reaction pathways, including the direct cleavage of ether bonds and the formation of intermediates with one hydrogenated benzene ring, for all examined types of ether bonds, namely, 4-O-5, α-O-4, and β-O-4.
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Affiliation(s)
- Zhimin Xue
- Beijing Key Laboratory of Lignocellulosic Chemistry, College of Materials Science and Technology, Beijing Forestry University, Beijing, 100083, PR China
| | - Haitao Yu
- Beijing Key Laboratory of Lignocellulosic Chemistry, College of Materials Science and Technology, Beijing Forestry University, Beijing, 100083, PR China
| | - Jing He
- Beijing Key Laboratory of Lignocellulosic Chemistry, College of Materials Science and Technology, Beijing Forestry University, Beijing, 100083, PR China
| | - Yibin Zhang
- Beijing Key Laboratory of Lignocellulosic Chemistry, College of Materials Science and Technology, Beijing Forestry University, Beijing, 100083, PR China
| | - Xue Lan
- Department of Chemistry, Renmin University of China, Beijing, 100872, PR China
| | - Rundong Liu
- Beijing Key Laboratory of Lignocellulosic Chemistry, College of Materials Science and Technology, Beijing Forestry University, Beijing, 100083, PR China
| | - Luyao Zhang
- Beijing Key Laboratory of Lignocellulosic Chemistry, College of Materials Science and Technology, Beijing Forestry University, Beijing, 100083, PR China
| | - Tiancheng Mu
- Department of Chemistry, Renmin University of China, Beijing, 100872, PR China
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12
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Focusing on the Catal. of the Pd- and Ni-Catalyzed Hirao Reactions. Molecules 2020; 25:molecules25173897. [PMID: 32859095 PMCID: PMC7503744 DOI: 10.3390/molecules25173897] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/24/2020] [Accepted: 08/25/2020] [Indexed: 12/17/2022] Open
Abstract
The Hirao reaction involving the phosphinoylation or phosphonation of aryl halides by >P(O)H reagents is a P–C bond forming transformation belonging to the recently very hot topic of cross-couplings. The Pd- or Ni-catalyzed variations take place via the usual cycle including oxidative addition, ligand exchange, and reductive elimination. However, according to the literature, the nature of the transition metal catalysts is not unambiguous. In this feature article, the catalysts described for the Pd(OAc)2-promoted cases are summarized, and it is concluded that the “(HOY2P)2Pd(0)” species (Y = aryl, alkoxy) is the real catalyst. In our model, the excess of the >P(O)H reagent served as the P-ligand. During the less studied Ni(II)-catalyzed instances the “(HOY2P)(−OY2P)Ni(II)Cl−” form was found to enter the catalytic cycle. The newest conclusions involving the exact structure of the catalysts, and the mechanism for their formation explored by us were supported by our earlier experimental data and theoretical calculations.
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13
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Nebra N. High-Valent Ni III and Ni IV Species Relevant to C-C and C-Heteroatom Cross-Coupling Reactions: State of the Art. Molecules 2020; 25:molecules25051141. [PMID: 32143336 PMCID: PMC7179250 DOI: 10.3390/molecules25051141] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 02/25/2020] [Accepted: 02/26/2020] [Indexed: 11/16/2022] Open
Abstract
Ni catalysis constitutes an active research arena with notable applications in diverse fields. By analogy with its parent element palladium, Ni catalysts provide an appealing entry to build molecular complexity via cross-coupling reactions. While Pd catalysts typically involve a M0/MII redox scenario, in the case of Ni congeners the mechanistic elucidation becomes more challenging due to their innate properties (like enhanced reactivity, propensity to undergo single electron transformations vs. 2e− redox sequences or weaker M–Ligand interaction). In recent years, mechanistic studies have demonstrated the participation of high-valent NiIII and NiIV species in a plethora of cross-coupling events, thus accessing novel synthetic schemes and unprecedented transformations. This comprehensive review collects the main contributions effected within this topic, and focuses on the key role of isolated and/or spectroscopically identified NiIII and NiIV complexes. Amongst other transformations, the resulting NiIII and NiIV compounds have efficiently accomplished: i) C–C and C–heteroatom bond formation; ii) C–H bond functionalization; and iii) N–N and C–N cyclizative couplings to forge heterocycles.
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Affiliation(s)
- Noel Nebra
- Laboratoire Hétérochimie Fondamentale et Appliquée, Université Paul Sabatier/CNRS UMR 5069, 118 Route de Narbonne, 31062 Toulouse, France
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14
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Shin J, Gwon S, Kim S, Lee J, Park K. Correlation between the C-C Cross-Coupling Activity and C-to-Ni Charge Transfer Transition of High-Valent Ni Complexes. J Am Chem Soc 2020; 142:4173-4183. [PMID: 32057242 DOI: 10.1021/jacs.9b10405] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
High-valent Ni complexes have proven to be good platforms for diverse cross-coupling reactions that are otherwise difficult to be achieved with conventional low-valent catalysts. However, their reductive elimination (RE) activities are still significantly variable by up to 5 orders of magnitude, depending on the supporting ligand and oxidation state of the Ni center. To elucidate frontier molecular orbitals (FMOs) that determine the RE activity of the Ni center, the electronic structures of cycloneophyl (CH2C(CH3)2-o-C6H4) NiIII and NiIV complexes have been characterized by utilizing various transition metal-based spectroscopic techniques such as electronic absorption, magnetic circular dichroism, electron paramagnetic resonance, resonance Raman, and X-ray absorption spectroscopies. In combination with density functional theory computations, the spectroscopic analyses have shown that the energies of the C-to-Ni charge-transfer (CT) electronic transitions are strongly correlated to the rates of C-C bond-forming RE reaction. This correlation suggests that the kinetic barrier of the RE reaction is determined by energy cost for internal CT (ICT) from the coordinated carbon moiety to the Ni center, and that FMOs involved in the RE reaction and the C-to-Ni CT electronic transitions are essentially identical. This FMO determination has led us to discover that photoexcitation to the C-to-Ni CT excited states accelerates the C-C cross-coupling reaction by up to 105 times, as the CT electronic transition can substitute for the rate-determining ICT step of the RE reaction at the ground electronic state.
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Affiliation(s)
- Jeongcheol Shin
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Suyeon Gwon
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Samhwan Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Jiseon Lee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Kiyoung Park
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
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15
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Roberts CC, Chong E, Kampf JW, Canty AJ, Ariafard A, Sanford MS. Nickel(II/IV) Manifold Enables Room-Temperature C(sp 3)-H Functionalization. J Am Chem Soc 2019; 141:19513-19520. [PMID: 31769667 DOI: 10.1021/jacs.9b11999] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
This Article demonstrates a mild oxidatively induced C(sp3)-H activation at a high-valent Ni center. In contrast with most C(sp3)-H activation reactions at NiII, the transformation proceeds at room temperature and generates an isolable NiIV σ-alkyl complex. Density functional theory studies show two plausible mechanisms for this C-H activation process involving triflate-assisted C-H cleavage at either a NiIV or a NiIII intermediate. The former pathway is modestly favored over the latter (by ∼3 kcal/mol). The NiIV σ-alkyl product of C-H cleavage reacts with a variety of nucleophiles to form C(sp3)-X bonds (X = halide, oxygen, nitrogen, sulfur, or carbon). These stoichiometric transformations can be coupled using N-fluoro-2,4,6-trimethylpyridinium triflate as a terminal oxidant in conjunction with chloride as a nucleophile to achieve a proof-of-principle NiII/IV-catalyzed C(sp3)-H functionalization reaction.
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Affiliation(s)
- Courtney C Roberts
- Department of Chemistry , University of Michigan , 930 North University Avenue , Ann Arbor , Michigan 48109 , United States
| | - Eugene Chong
- Department of Chemistry , University of Michigan , 930 North University Avenue , Ann Arbor , Michigan 48109 , United States
| | - Jeff W Kampf
- Department of Chemistry , University of Michigan , 930 North University Avenue , Ann Arbor , Michigan 48109 , United States
| | - Allan J Canty
- School of Natural Sciences - Chemistry , University of Tasmania , Hobart , Tasmania 7001 , Australia
| | - Alireza Ariafard
- School of Natural Sciences - Chemistry , University of Tasmania , Hobart , Tasmania 7001 , Australia
| | - Melanie S Sanford
- Department of Chemistry , University of Michigan , 930 North University Avenue , Ann Arbor , Michigan 48109 , United States
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Steen JS, Knizia G, Klein JEMN. σ-Noninnocence: Masked Phenyl-Cation Transfer at Formal Ni IV. Angew Chem Int Ed Engl 2019; 58:13133-13139. [PMID: 31206937 PMCID: PMC6771483 DOI: 10.1002/anie.201906658] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Indexed: 12/31/2022]
Abstract
Reductive elimination is an elementary organometallic reaction step involving a formal oxidation state change of -2 at a transition-metal center. For a series of formal high-valent NiIV complexes, aryl-CF3 bond-forming reductive elimination was reported to occur readily (Bour et al. J. Am. Chem. Soc. 2015, 137, 8034-8037). We report a computational analysis of this reaction and find that, unexpectedly, the formal NiIV centers are better described as approaching a +II oxidation state, originating from highly covalent metal-ligand bonds, a phenomenon attributable to σ-noninnocence. A direct consequence is that the elimination of aryl-CF3 products occurs in an essentially redox-neutral fashion, as opposed to a reductive elimination. This is supported by an electron flow analysis which shows that an anionic CF3 group is transferred to an electrophilic aryl group. The uncovered role of σ-noninnocence in metal-ligand bonding, and of an essentially redox-neutral elimination as an elementary organometallic reaction step, may constitute concepts of broad relevance to organometallic chemistry.
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Affiliation(s)
- Jelte S. Steen
- Molecular Inorganic ChemistryStratingh Institute for ChemistryFaculty of Science and EngineeringUniversity of GroningenNijenborgh 49747AGGroningenThe Netherlands
| | - Gerald Knizia
- Department of ChemistryPennsylvania State University401A Chemistry BldgUniversity ParkPA16802USA
| | - Johannes E. M. N. Klein
- Molecular Inorganic ChemistryStratingh Institute for ChemistryFaculty of Science and EngineeringUniversity of GroningenNijenborgh 49747AGGroningenThe Netherlands
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17
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Steen JS, Knizia G, Klein JEMN. σ‐Noninnocence: Masked Phenyl‐Cation Transfer at Formal Ni
IV. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201906658] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Jelte S. Steen
- Molecular Inorganic Chemistry Stratingh Institute for Chemistry Faculty of Science and Engineering University of Groningen Nijenborgh 4 9747 AG Groningen The Netherlands
| | - Gerald Knizia
- Department of Chemistry Pennsylvania State University 401A Chemistry Bldg University Park PA 16802 USA
| | - Johannes E. M. N. Klein
- Molecular Inorganic Chemistry Stratingh Institute for Chemistry Faculty of Science and Engineering University of Groningen Nijenborgh 4 9747 AG Groningen The Netherlands
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